Latest revision as of 11:51, July 7, 2013

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Since the discovery of many new override features, some far surpassing what the cameras were originally sold to do, it has been found that each make and model of camera may have variations in the absolute limits of Shutter-Speeds, F-Stops, ISO-Values, Motion-Detection Speed, among others.

It might be interesting if people who have tested the limits of their particular cameras would provide what limits they found. This would also be a nice quick & dirty chart for anyone wanting to choose a CHDK-capable camera based on these new capabilities. As well as a place to show to newcomers the answer to their "I set my camera to 2 minutes exposure but I only get 65 seconds, Why" questions.

NOTE: All ratings in this chart should be taken as a basic guideline. These were not tested in labs and we have to depend on the creative ways and know-how of each individual camera user that might have tested them. Also, due to discrepancies in build-quality from camera to camera, you may find that your particular camera may not attain or might even surpass the ratings that others might have listed here.

Important! -- Just because you can set an override shutter-speed, f/stop or ISO sensitivity on your camera with CHDK, it doesn't mean your camera can actually do that setting. Be sure you have tested to make sure that extreme setting is actually making a difference in your resulting images. Listing here the available numbers that are built into CHDK will do no good. Those numbers can go well outside of your camera's capabilities. You might select an f/stop of f/16, but it doesn't mean you are actually obtaining that desired setting. EXIF will even record your chosen setting, but it may not actually be applying it to your image. Find ways to test them, to be sure you are actually getting those limits. This list should be a reference of TRUE limits of your cameras, not the possible ones that are only written into CHDK.

1 RAW File/Frame Sizes - You might notice something you haven't noticed before. In most cameras the RAW image dimensions (not just file-size) are larger than the resulting JPG file dimensions that the camera creates. This is due to the need to throw away pixels around the border, pixels that contain real image data (just beyond your normal viewfinder's FOV). In-camera RAW interpolation routines are not very "intelligent" and don't know how to deal with these border pixels. More advanced editing software usually doesn't have this problem. For example: If you look at the S3 IS data here, you'll see that the RAW image dimensions are 2840 x 2128 and the JPG is 2816 x 2112. That's an extra 24 pixels horizontally and 16 pixels vertically in the RAW image. If the JPG is defining a 36mm (35mm eq.) lens FOV then the RAW is showing you a 35.7mm (35mm eq.) FOV. You might be getting almost an extra 1/3 to 1/2mm focal length of extra wide-angle image data for free with the CHDK RAW image. (Another small perk to shooting with RAW in these cameras.)

2 Min. volts for USB Remote - It has been found that some camera models are more sensitive on what minimum voltage must be used to get the USB-Remote features to trigger cleanly and properly. Not too long ago most cameras that were supported with USB-Remote feature only need a 3V button-cell for the trigger. Today this is no longer true and 3 stacked 1.5v cells (4.5v) might be needed for some cameras. This voltage information would probably be better in some other page in the Wikia, like the Scripting Tutorial or other places that USB-Remote is explained, but for data-collecting purposes this chart might be a good place to collect this info (for now).

Wakes up on USB signal means whether the off-state camera is switching on when a USB signal is detected.

If when checking your RAW file-sizes for this chart, you might want to consider adding a sample RAW image to this online archive http://www.rawsamples.ch/ Developers of programs have started using this as a resource for samples from many kinds of cameras. If they have samples of these non-standard CHDK RAW formats, more editing and viewing programs might support them one day.

5 Although it seems strange, a difference is still visible between 1/25,000 and 1/33,333 at f/2.7 on the S5IS. That particular test was conducted with a 'non-moving' object (the sun). Later tests, however at f/8 and with full flash, show a 6-degree rotation on a dremel disk turning at 33,000rpm. A quick calculation shows 1/32,520 for the shutter time. At minimal flash, the disk is rotated by just 0.9 degrees, which means a 1/224,000 shutter/flash time. Someone might want to verify these values some time soon, as they look pretty extreme.

By the way, when using the Speedlite 580EX II, OEM flash sync will work all the way to 1/3,200", when the flash is set to highspeed mode. Regardless, the external flash syncs even at 1/33,333" with 1/128 strength. Setting the 580EX II to 1/1 does not generate the expected amount of extra exposure, the flash unit probably requires more than 1/33,333" to reach full power. A quick test (though on a 160cm (5 1/3 ft) offshoe cord) shows that the camera syncs with the flash on 1/33,333", though exposure seems to stop increasing around or just slightly weaker than 1/16. It still syncs at 1/1, but the exposure is the same as 1/16. Also, the exposure at these intensities differs in shoots with the same settings, so it's likely to assume that the sync isn't always perfect and probably lags a bit. For the record: the Speedlite had to recycle a lot longer than normal, so the batteries were probably almost dead. While this does not affect flash intensity, it may cause the internal circuitry to run a bit slower and throw off these measurements. It also seems that ETTL works at this shutter speed. Judging by the sound the flash makes, the second flash is more intense than the preflash and does register on the image (manual flash set to the estimateed preflash strength gives less exposure). This is hard to test and judge, though, I might be wrong.

6 1.15V Seems suspiciously low compared to other cameras, but that's what I measured using my multimeter and an adjustable power supply. I'm using 2xAA battery (3V) with no problems.

7 2500 may not be achievable, to be sure it would need further testing. 1600 seems to be the maximum by some recent (non scientific) testing. An0n: 01/08/09.

8 Values outside these limits can be set in CHDK and are taken into account by the automatic exposure system, but in reality, ISO stays fixed at 80/800, resulting in overexposed/underexposed images. ISO values set in CHDK need to be multiplied by approx. 1.5 to correspond to those reported by the camera on the display and in the EXIF data (reported ISO 800 ˜ CHDK ISO 530). The camera's physical sensitivity is limited to ISO 800; at ISO settings above 800, the camera automatically brightens up the image by the corresponding EV value. This automatic brightening-up is for some reason disabled when the sensitivity is set by CHDK (either via manual ISO override or via Custom auto ISO function), so JPEGs with ISO above 800 come out underexposed (raw files above ISO 800 are always underexposed, regardless of whether the ISO was set by CHDK or the camera).

Contributors: When adding your own findings to this chart, simply click on the [edit] link just above and to the right of the chart. In your editing window scroll down to your camera model, and insert the information in this sequence:

NOTE: Absolute fastest shutter-speeds available only with highest f/stops.

Due to these new shutter speeds being much faster than any consumer-grade cameras on the market, some rather inventive ways had to be found to determine their true top limits. Please read the following pages and discussions just to see what we were up against in trying to do so, therein you'll find the best ways to test your own camera.

Put your lens set to the longest focal-length (longest zoom) and then (using the method described below by Allbest for ISO tests), use Av bracketing mode.

1. Go to menu Extra Photo Operations > Override Aperture > Set to any value at or below your camera's smallest (highest number) aperture. Ex: if your camera's highest f/stop is f/8.0, set it to some value at or just below that. (This way you have a known reference frame to start with.) OR, put your camera in Av Priority Mode, and set it for a small aperture.

CHDK Forum Discussion "Motion Detection Too Slow" That discussion thread includes some new high-speed scripts and a testing program "MD-Test v2" (by "jonnythe) whereby you can test your camera's motion-detection response time just by photographing your computer screen. (read thread for info on use and optimum md-detection script settings)